numerous: most parts, especially Cork and Munster generally. Ir. Mac Suibhne, from first name Suibhne "well-disposed". The name came from Donegal where they were Scottish galloglasses in 14 cent. Ironically, in Donegal, the name is now Sweeney.

MacSwiney:

Quite numerous: Cork etc. Variant of Mac Sweeney, q.v.

Sweeney:

Very numerous: all areas, especially Donegal-Derry. Ir. Mac Suibhne (pleasant). They were Scottish galloglasses who establishd three septs in Donegal and a branch in Cork. See also Mac Sweeney and Mac Swiney. IF.